Apparatus for wireless communication

ABSTRACT

[Object] To suppress the overhead related to the transmission of the reference signal when beamforming is performed. 
     [Solution] Provided is an apparatus, including: an acquiring unit configured to acquire antenna-related information related to an antenna port allocated to a directional beam for transmission by the directional beam; and a notifying unit configured to notify a terminal apparatus of the antenna-related information.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/542,090, filed Jul. 7, 2017, which is based on PCT filingPCT/JP2016/054303, filed Feb. 15, 2016, and claims priority to JP2015-061307, filed Mar. 24, 2015, the entire contents of each areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to apparatuses.

BACKGROUND ART

In the Third Generation Partnership Project (3GPP), various techniquesfor improving the capacity of a cellular system are currently studied inorder to accommodate explosively increasing traffic. It is alsoenvisaged that the required capacity will become about 1000 times thecurrent capacity in the future. Techniques such as multi-usermulti-input multiple-input multiple-output (MU-MIMO), coordinatedmultipoint (CoMP), and the like could increase the capacity of acellular system by a factor of as low as less than ten. Therefore, thereis a demand for an innovative technique.

For example, as a technique for significantly increasing the capacity ofa cellular system, a base station may perform beamforming using adirectional antenna including a large number of antenna elements (e.g.,about 100 antenna elements). Such a technique is a kind of techniquecalled large-scale MIMO, massive MIMO, or free dimension (FD)-MIMO. Bysuch beamforming, the half-width of a beam is narrowed. In other words,a sharp beam is formed. Also, if the large number of antenna elementsare arranged in a plane, a beam aimed in a desired three-dimensionaldirection can be formed.

For example, Patent Literatures 1 to 3 disclose techniques applied whena directional beam aimed in a three-dimensional direction is used.

CITATION LIST Patent Literature

Patent Literature 1: JP 2014-204305A

Patent Literature 2: JP 2014-53811A

Patent Literature 3: JP 2014-64294A

DISCLOSURE OF INVENTION Technical Problem

When large-scale MIMO (that is, massive MIMO or FD-MIMO) is employed,for example, an antenna having a large number of antenna elements (forexample, about 64 to hundreds of antenna elements) is used. As thenumber of antenna elements increases, the number of antenna ports isalso expected to increase explosively. For this reason, for transmissionof a reference signal (for example, a demodulation reference signal(DMRS)) using a plurality of antenna ports, a plurality of orthogonalresources are prepared, and thus the overhead related to thetransmission of the reference signal may be increased. The increase inthe number of antenna ports and the overhead occur even when beamformingis performed.

In this regard, it is desirable to provide a mechanism capable ofsuppressing the overhead related to the transmission of the referencesignal when beamforming is performed.

Solution to Problem

According to the present disclosure, there is provided an apparatus,including: an acquiring unit configured to acquire antenna-relatedinformation related to an antenna port allocated to a directional beamfor transmission by the directional beam; and a notifying unitconfigured to notify a terminal apparatus of the antenna-relatedinformation.

Further, according to the present disclosure, there is provided anapparatus, including: an acquiring unit configured to acquireantenna-related information related to an antenna port allocated to adirectional beam for transmission by the directional beam; and areception processing unit configured to perform a reception process onthe basis of the antenna-related information.

Advantageous Effects of Invention

As described above, according to the present disclosure, it is possibleto suppress the overhead related to the transmission of the referencesignal when beamforming is performed. Note that the effects describedabove are not necessarily limitative. With or in the place of the aboveeffects, there may be achieved any one of the effects described in thisspecification or other effects that may be grasped from thisspecification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for describing a weight set for large-scale MIMObeamforming.

FIG. 2 is a diagram for describing a relationship between multiplicationof weight coefficients and insertion of a reference signal.

FIG. 3 is an explanatory diagram for describing an example of resourcesin which a DMRS is transmitted using antenna ports 7, 8, 11, and 13 in atransmission mode 9.

FIG. 4 is an explanatory diagram for describing an example of resourcesin which a DMRS is transmitted using antenna ports 9, 10, 12, and 14 inthe transmission mode 9.

FIG. 5 is an explanatory diagram for describing an example of anenvironment in which a directional beam is not reflected.

FIG. 6 is an explanatory diagram for describing an example of anenvironment in which a directional beam is reflected.

FIG. 7 is an explanatory diagram illustrating an example of a schematicconfiguration of a system according to an embodiment.

FIG. 8 is a block diagram showing an example of a configuration of abase station according to the embodiment.

FIG. 9 is a block diagram showing an example of a configuration of aterminal apparatus according to the embodiment.

FIG. 10 is an explanatory diagram for describing an example ofdirectional beams formed by a base station.

FIG. 11 is an explanatory diagram for describing an example of antennaports allocated to respective directional beams.

FIG. 12 is an explanatory diagram for describing an example oftransmission by respective beams in resources for transmitting areference signal.

FIG. 13 is an explanatory diagram for describing an example ofdirectional beams formed by a base station.

FIG. 14 is an explanatory diagram for describing an example of antennaports allocated to respective directional beams in accordance withanother technique (a technique of preparing a different antenna port foreach directional beam).

FIG. 15 is an explanatory diagram for describing an example oftransmission by respective beams in another technique.

FIG. 16 is an explanatory diagram for describing an example of antennaports allocated to respective directional beams by a first technique.

FIG. 17 is an explanatory diagram for describing an example oftransmission by respective beams in a first technique.

FIG. 18 is an explanatory diagram for describing an example of antennaports allocated to respective directional beams by a second technique.

FIG. 19 is an explanatory diagram for describing an example ofdirectional beams formed by a base station.

FIG. 20 is an explanatory diagram for describing an example of antennaports allocated to respective directional beams by a third technique.

FIG. 21 is an explanatory diagram for describing an example oftransmission by respective beams in a third technique.

FIG. 22 is an explanatory diagram for describing an example ofdirectional beams formed by a base station.

FIG. 23 is an explanatory diagram for describing an example of antennaports allocated to respective directional beams by a fourth technique.

FIG. 24 is an explanatory diagram for describing an example oftransmission by respective beams in a fourth technique.

FIG. 25 is a flowchart illustrating a first example of a schematic flowof a transmission/reception process according to the embodiment.

FIG. 26 is a flowchart illustrating a second example of a schematic flowof a transmission/reception process according to the embodiment.

FIG. 27 is a flowchart illustrating an example of a schematic flow of anantenna port allocation process according to the embodiment.

FIG. 28 is a block diagram illustrating a first example of a schematicconfiguration of an eNB.

FIG. 29 is a block diagram illustrating a second example of theschematic configuration of the eNB.

FIG. 30 is a block diagram illustrating an example of a schematicconfiguration of a smartphone.

FIG. 31 is a block diagram illustrating an example of a schematicconfiguration of a car navigation apparatus.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, (a) preferred embodiment(s) of the present disclosure willbe described in detail with reference to the appended drawings. In thisspecification and the appended drawings, structural elements that havesubstantially the same function and structure are denoted with the samereference numerals, and repeated explanation of these structuralelements is omitted.

Description will be given in the following order.

-   1. Introduction-   1.1. Technology related to beamforming-   1.2. Technical problems-   2. Schematic configuration of system-   3. Configuration of each apparatus-   3.1. Configuration of base station-   3.2. Configuration of terminal apparatus-   4. Technical features-   5. Processing flow-   6. Application examples-   6.1. Application examples for base station-   6.2. Application examples for terminal apparatus-   7. Conclusion

<<1. Introduction>>

First, a technique related to beamforming and technical features relatedto an embodiment of the present disclosure will be described withreference to FIGS. 1 to 6.

<1.1. Technology Related to Beamforming>

A technique related to beamforming will be described with reference toFIGS. 1 to 6.

(1) Necessity of Large-Scale MIMO

In the 3GPP, various techniques for improving the capacity of a cellularsystem are currently studied in order to accommodate explosivelyincreasing traffic. It is envisaged that the required capacity willbecome about 1000 times the current capacity in the future. Techniquessuch as MU-MIMO, CoMP, and the like could increase the capacity of acellular system by a factor of as low as less than ten. Therefore, thereis a demand for an innovative technique.

Release 10 of the 3GPP specifies that evolved eNode B is equipped witheight antennas. Therefore, the antennas can provide eight-layer MIMO inthe case of single-user multi-input multiple-input multiple-output(SU-MIMO). Eight-layer MIMO is a technique of spatially multiplexingeight separate streams. Alternatively, the antennas can providefour-user two-layer MU-MIMO.

User equipment (UE) has only a small space for accommodating an antenna,and limited processing capability, and therefore, it is difficult toincrease the number of antenna elements in the antenna of UE. However,recent advances in antenna mounting technology have allowed eNode B toaccommodate a directional antenna including about 100 antenna elements.

For example, as a technique for significantly increasing the capacity ofa cellular system, a base station may perform beamforming using adirectional antenna including a large number of antenna elements (e.g.,about 100 antenna elements). Such a technique is a kind of techniquecalled large-scale MIMO or massive MIMO. By such beamforming, thehalf-width of a beam is narrowed. In other words, a sharp beam isformed. Also, if the large number of antenna elements are arranged in aplane, a beam aimed in a desired three-dimensional direction can beformed. For example, it has been proposed that, by forming a beam aimedat a higher position than that of a base station (e.g., a higher floorof a high-rise building), a signal is transmitted to a terminalapparatus located at that position.

In typical beamforming, it is possible to control a direction of a beamin the horizontal direction. Therefore, the typical beamforming can beregarded as two-dimensional beamforming. On the other hand, inbeamforming of large-scale MIMO (or massive MIMO), it is possible tocontrol a direction of a beam in the vertical direction in addition tothe horizontal direction. In other words, it is possible to form athree-dimensional beam having desired directivity in the horizontaldirection and the vertical direction. Therefore, beamforming oflarge-scale MIMO can be regarded as 3-dimensional beamforming. Forexample, a three-dimensional beam can be formed using antenna elementswhich are arranged two dimensionally.

Note that the increase in the number of antennas allows for an increasein the number of MU-MIMO users. Such a technique is another form of thetechnique called large-scale MIMO or massive MIMO. Note that when thenumber of antennas in UE is two, the number of spatially separatedstreams is two for a single piece of UE, and therefore, it is morereasonable to increase the number of MU-MIMO users than to increase thenumber of streams for a single piece of UE.

(2) Weight Set

A set of weight for beamforming are represented by a complex number(i.e., a set of weight coefficients for a plurality of antennaelements). An example of a weight set particularly for large-scale MIMObeamforming will now be described with reference to FIG. 1.

FIG. 1 is a diagram for describing a weight set for large-scale MIMObeamforming. FIG. 1 shows antenna elements arranged in a grid pattern.FIG. 1 also shows two orthogonal axes x and y in a plane in which theantenna elements are arranged, and an axis z perpendicular to the plane.Here, the direction of a beam to be formed is, for example, representedby an angle phi (Greek letter) and an angle theta (Greek letter). Theangle phi (Greek letter) is an angle between an xy-plane component ofthe direction of a beam and the x-axis. Also, the angle theta (Greekletter) is an angle between the beam direction and the z-axis. In thiscase, for example, the weight coefficient V_(m,n) of an antenna elementwhich is m-th in the x-axis direction and n-th in the y-axis directionis represented as follows.

$\begin{matrix}{{V_{m,n}\left( {\theta,\phi,f} \right)} = {\exp \left( {j\; 2\; \pi \frac{f}{c}\left\{ {{\left( {m - 1} \right)d_{x}{\sin (\theta)}{\cos (\phi)}} + {\left( {n - 1} \right)d_{y}{\sin (\theta)}{\sin (\phi)}}} \right\}} \right)}} & \left\lbrack {{Math}.\mspace{14mu} 1} \right\rbrack\end{matrix}$

In formula (1), f is a frequency, and c is the speed of light. Also, jis the imaginary unit of a complex number. Also, d_(x) is an intervalbetween each antenna element in the x-axis direction, and d_(y) is aninterval between each antenna element in the y-axis direction. Note thatthe coordinates of an antenna element are represented as follows.

x=(m−1)d _(x) , y=(n−1)d _(y)   [Math. 2]

A weight set for typical beamforming (two-dimensional beamforming) canbe split into a weight set for obtaining directivity in the horizontaldirection and a weight set for phase adjustment of multilayer MIMO (forexample, dual layer MIMO) (for example, a weight set for phaseadjustment between two antenna sub arrays corresponding to differentpolarized waves). On the other hand, a weight set for beamforming oflarge-scale MIMO (three-dimensional beamforming) can be split into afirst weight set for obtaining directivity in the horizontal direction,a second weight set for obtaining directivity in the vertical direction,and a third weight set for phase adjustment of multilayer MIMO (forexample, dual layer MIMO). For example, the third weight set is a weightset for phase adjustment between sub arrays. Further, when transmissionis performed in a single layer, the weight set for phase adjustment ofmultilayer MIMO (for example, dual layer MIMO) may not be included.

(3) Reception of Signal

For demodulation of a signal transmitted over a directional beam, anevolved Node B (eNB) transmits a DMRS along with a data signal in thedownlink. The DMRS is a sequence known to the UE and is multiplied by aset of weight coefficients for beamforming (which is the same as a setof weight coefficients multiplied by a data signal). The UE restores aphase and an amplitude of the data signal on the basis of a receptionresult of the DMRS, and demodulates and decodes the data signal.

(4) DMRS

(a) Difference of CRS and CSI-RS with DMRS

In LTE, in addition to the DMRS, there are reference signals such as acell-specific reference signal (CRS) and a channel state informationreference signal (CSI-RS). The CRS and the CSI-RS are not used fordemodulation of the data signal but are mainly used for measuring achannel quality. Specifically, the CRS is used for cell selection, andthe CSI-RS is used for determining a modulation scheme. Therefore,according to the current standard, the CRS and the CSI-RS are nottransmitted by a directional beam but transmitted by non-directionalradio waves.

Note that the CRS and/or the CSI-RS may be transmitted by a directionalbeam. Depending on a system design concept at that time, the CRS and/orthe CSI-RS is transmitted by the non-directional radio wave or istransmitted by the directional beam.

On the other hand, since the DMRS is transmitted for demodulation of thedata signal transmitted by the directional beam, it is similarlytransmitted by the directional beam.

An example of multiplication of the reference signal and the weightcoefficient will be described with reference to FIG. 2. FIG. 2 is adiagram for describing the relationship between multiplication of weightcoefficients and insertion (or mapping) of a reference signal. Referringto FIG. 2, a transmission signal 82 corresponding to each antennaelement 81 is complex-multiplied by a weight coefficient 83 by amultiplier 84. Thereafter, the transmission signal 82 complex-multipliedby the weight coefficient 83 is transmitted from the antenna element 81.Also, a DR-MS 85 is inserted before the multiplier 84, and iscomplex-multiplied by the weight coefficient 83 by the multiplier 84.Thereafter, the DR-MS 85 complex-multiplied by the weight coefficient 83is transmitted from the antenna element 81. Meanwhile, a CRS 86 (and aCSI-RS) is inserted after the multiplier 84. Thereafter, the CRS 86 (andthe CSI-RS) is transmitted from the antenna element 81 without beingmultiplied by the weight coefficient 83.

(b) Example of Resources Used for DMRS Transmission

The DMRS is transmitted using a corresponding antenna port. Further, theDMRS is transmitted in resources associated with the correspondingantenna port. The resources indicate a combination of time/frequencyresources and a code sequence. The resources associated with any oneantenna port and the resources associated with another antenna port areorthogonal to each other. In other words, the resources associated withany one antenna port and the resources associated with another antennaport differ in at least one of the time/frequency resources and the codesequence. An example of resources in which the DMRS is transmitted willbe described with reference to FIGS. 3 and 4.

FIG. 3 is an explanatory diagram for describing an example of resourcesin which the DMRS is transmitted using antenna ports 7, 8, 11, and 13 ina transmission mode 9. Referring to FIG. 3, two resource blocks arrangedin a time direction are illustrated. As illustrated in FIG. 3, for theantenna ports 7, 8, 11, and 13, twelve resource elements are prepared asthe resource elements for the DMRS. The eNB uses the antenna ports 7, 8,11, and 13 to transmit the DMRS through the resource elements.Particularly, in order to allocate orthogonal resources to antenna ports7, 8, 11, and 13 (in a pseudo manner), the following code sequences areapplied to the

-   -   antenna ports 7, 8, 11, and 13:    -   antenna port 7: +1, +1, +1, +1    -   antenna port 8: +1, −1, +1, −1    -   antenna port 11: +1, +1, −1, −1    -   antenna port 13: +1, −1, −1, +1

FIG. 4 is an explanatory diagram for describing an example of resourcesin which the DMRS is transmitted using the antenna ports 9, 10, 12, and14 in the transmission mode 9. Referring to FIG. 4, two resource blocksarranged in the time direction are illustrated. As illustrated in FIG.4, for the antenna ports 9, 10, 12, and 14, twelve resource elements areprepared as the resource elements for the DMRS. The eNB uses the antennaports 9, 10, 12, and 14 to transmit the DMRS through the resourceelements. The twelve resource elements illustrated in FIG. 4 areorthogonal to the twelve resource elements illustrated in FIG. 3 interms of frequency. In other words, the resources associated with theantenna ports 9, 10, 12, and 14 are orthogonal to the resourcesassociated with the antenna ports 7, 8, 11, and 13. Furthermore, inorder to allocate orthogonal resources to the antenna ports 9, 10, 12,and 14 (in a pseudo manner), the following code sequences are applied tothe antenna ports 9, 10, 12, and 14:

antenna port 9: +1, +1, +1, +1

antenna port 10: +1, −1, +1, −1

antenna port 12: −1, −1, +1, +1

antenna port 14: −1, +1, +1, −1

As described above, the resources associated with any one antenna portare orthogonal to the resources associated with another antenna port.For example, the UE including two antennas can receive signals from theeight antenna ports and calculate an 8×2 channel matrix.

(5) Antenna Port

(a) Virtual Antenna

In LTE, instead of a physical antenna/antenna element, a virtual antennasuch as an antenna port is prepared. The antenna port corresponds to oneor more physical antennas or antenna elements, but a specificcorrespondence relation between the antenna port and the antenna/antennaelement depends on an implementation and has a degree of freedom. Forexample, one antenna port may correspond to one antenna (for example,one normal antenna or one array antenna). Further, for example, oneantenna port may correspond to one antenna element (or a plurality ofantenna elements) included in an array antenna.

(b) Resources Associated with Antenna Port

As described above, for example, for a plurality of antenna ports, aplurality of orthogonal resources (a combination of time/frequencyresources and a code sequence) are prepared and used for transmission ofthe DMRS. For example, the eNB transmits the DMRS in first resourcesusing a first antenna port (for example, the antenna port 10) andtransmits the DMRS in second resources orthogonal to the first resourcesusing a second antenna port (for example, the antenna port 11).

(c) Reason for Preparing Orthogonal Resources

Since each antenna port corresponds to an antenna/antenna elementlocated at a spatially different position, a spatially independentchannel is obtained between the eNB and the UE. Before the orthogonalchannel is obtained, it is necessary to estimate a channelcharacteristic on the basis of the reference signal (for example, theDMRS). Since it is difficult to estimate a channel characteristic wheninterference with the reference signal occurs, orthogonal resources(that is, different resources) are prepared for each antenna port sothat interference does not occur between the reference signalstransmitted using different antenna ports.

For example, the eNB includes two antennas (for example, virtually twoantenna ports), and the UE includes two antennas as well. In this case,a channel matrix H (2×2) is calculated from a transfer function of 4(2×2) channels. Then, a general inverse matrix of the channel matrix His calculated, and two spatially independent channels are obtained bymultiplying reception data by the general inverse matrix from the leftside. Particularly, in order to properly calculate the channel matrix H,orthogonal resources (that is, different resources) are prepared foreach of two antenna ports so that no interference occurs between thereference signals transmitted using the two antenna ports.

(6) Interference Between Directional Beams

In an environment in which the directional beam formed by the eNB isreflected, the directional beam may interfere with other directionalbeams that are close to the directional beam in the radiation directiondue to the reflection by the directional beam. This point will bedescribed with reference to FIGS. 5 and 6 using a specific example.

FIG. 5 is an explanatory diagram for describing an example of anenvironment in which the directional beam is not reflected. Referring toFIG. 5, an eNB 11 and UEs 21, 23, and 25 are illustrated. For example,the eNB 11 forms a directional beam 31 for the UE 21, a directional beam33 for the UE 23, and a directional beam 35 for the UE 25. In thisexample, the directional beams 31, 33, and 35 are not reflected, andinterference does not occur among the directional beams 31, 33, and 35.

FIG. 6 is an explanatory diagram for describing an example of anenvironment in which the directional beam is reflected. Referring toFIG. 6, an eNB 11 and UEs 21, 23, and 25 are illustrated. In addition,obstacles 41 and 43 are illustrated. For example, the obstacles 41 and43 are buildings. For example, the eNB 11 forms a directional beam 31for the UE 21, a directional beam 33 for the UE 23, and a directionalbeam 35 for the UE 25. In this example, the directional beam 35 isreflected by the obstacles 41 and 43 and reaches the UE 23. Therefore,interference occurs between the directional beam 33 and the directionalbeam 35.

As described above, interference may occur between the directional beamsdue to the reflection, but a possibility of interference occurringbetween two directional beams having completely different radiationdirections is considered to be low.

<1.2. Technical Problems>

Next, technical problems related to an embodiment of the presentdisclosure will be described.

When large-scale MIMO (that is, massive MIMO or FD-MIMO) is employed,for example, an antenna having a large number of antenna elements (forexample, 64 to hundreds of antenna elements) is used. As the number ofantenna elements increases, the number of antenna ports is also expectedto increase explosively. For this reason, for transmission of areference signal (for example, a DMRS) using a plurality of antennaports, a plurality of orthogonal resources are prepared, and thus theoverhead related to the transmission of the reference signal may beincreased.

The increase in the number of antenna ports and the overhead occur evenwhen beamforming is performed. More specifically, for example, when thebeamforming is performed by the base station, if the radiationdirections of the two directional beams are close to each other,interference may occur between the two directional beams due toreflection (particularly, when beamforming of large-scale MIMO isperformed, a possibility of the occurrence of interference is consideredto be high due to reflection). In this regard, for example, if differentantenna ports are used for transmitting a signal through the twodirectional beams, a terminal apparatus may separate a reception signalinto a signal transmitted by one directional beam and a signaltransmitted by the other directional beam through a technique such asinterference cancellation (for example, successive interferencecancellation (SIC), parallel interference cancellation (PIC), or thelike). Due to such advantages, a plurality of antenna ports can be usedeven when beamforming is performed. As a result, the overhead may beincreased.

However, since a possibility of interference occurring betweendirectional beams having greatly different radiation directions is low,the same antenna ports rather than different antenna ports may be usedfor transmission of a signal by the directional beam. If this point isconsidered, it is possible to prevent the number of antenna ports frombeing unnecessarily increased when beamforming is performed.

In this regard, it is desirable to provide a mechanism capable ofsuppressing the overhead related to the transmission of the referencesignal when beamforming is performed.

<<2. Schematic Configuration of System>>

Next, a schematic configuration of a communication system 1 according toan embodiment of the present disclosure will be described with referenceto FIG. 7. FIG. 7 is a diagram for describing an example of theschematic configuration of the communication system 1 according to anembodiment of the present disclosure. Referring to FIG. 7, the system 1includes a base station 100 and terminal apparatuses 200. The system 1is a system which complies with, for example, LTE, LTE-Advanced, orsimilar communication standards.

(1) Base Station 100

The base station 100 performs wireless communication with the terminalapparatuses 200. For example, the base station 100 performs wirelesscommunication with the terminal apparatuses 200 located in a cell 101 ofthe base station 100.

Particularly, in an embodiment of the present disclosure, the basestation 100 performs beamforming. For example, the beamforming isbeamforming of large-scale MIMO. The beamforming may also be referred toas beamforming of massive MIMO, beamforming of free dimension (FD)-MIMOor three-dimensional beamforming. Specifically, for example, the basestation 100 includes a directional antenna usable for large-scale MIMOand performs beamforming of large-scale MIMO by multiplying atransmission signal by a weight set for the directional antenna.

(2) Terminal Apparatus 200

The terminal apparatus 200 performs wireless communication with the basestation 100. For example, the terminal apparatus 200 performs wirelesscommunication with the base station 100 when located in the cell 101 ofthe base station 100.

<<3. Configuration of Each Apparatus>>

Next, examples of configurations of the base station 100 and theterminal apparatus 200 will be described with reference to FIGS. 8 and9.

<3.1. Configuration of Base Station>

First of all, an example of the configuration of the base station 100according to an embodiment of the present disclosure will be describedwith reference to FIG. 8. FIG. 8 is a block diagram showing an exampleof the configuration of the base station 100 according to the embodimentof the present disclosure. Referring to FIG. 8, the base station 100includes an antenna unit 110, a wireless communication unit 120, anetwork communication unit 130, a storage unit 140, and a processingunit 150.

(1) Antenna Unit 110

The antenna unit 110 radiates a signal output by the wirelesscommunication unit 120, in the form of radio waves, into space. Theantenna unit 110 also converts radio waves in space into a signal, andoutputs the signal to the wireless communication unit 120.

For example, the antenna unit 110 includes a directional antenna. Forexample, the directional antenna is a directional antenna which can beused in large-scale MIMO.

(2) Wireless Communication Unit 120

The wireless communication unit 120 transmits and receives signals. Forexample, the wireless communication unit 120 transmits a downlink signalto the terminal apparatus 200 and receives an uplink signal from theterminal apparatus 200.

(3) Network Communication Unit 130

The network communication unit 130 transmits and receives information.For example, the network communication unit 130 transmits information toother nodes and receives information from other nodes. For example, theother nodes include other base stations and a core network node.

(4) Storage Unit 140

The storage unit 140 stores programs and data for operation of the basestation 100.

(5) Processing Unit 150

The processing unit 150 provides various functions of the base station100. The processing unit 150 includes an allocating unit 151, aninformation acquiring unit 153, and a notifying unit 155. Note that theprocessing unit 150 may further include other components in addition tosuch components. That is, the processing unit 150 may perform operationsother than operations of such components.

Specific operations of the allocating unit 151, the informationacquiring unit 153, and the notifying unit 155 will be described laterin detail.

<3.2. Configuration of Terminal Apparatus>

Next, an example of the configuration of the terminal apparatus 200according to an embodiment of the present disclosure will be describedwith reference to FIG. 9. FIG. 9 is a block diagram for showing anexample of the configuration of the terminal apparatus 200 according tothe embodiment of the present disclosure. Referring to FIG. 9, theterminal apparatus 200 includes an antenna unit 210, a wirelesscommunication unit 220, a storage unit 230 and a processing unit 240.

(1) Antenna Unit 210

The antenna unit 210 radiates a signal output by the wirelesscommunication unit 220, in the form of radio waves, into space. Theantenna unit 210 also converts radio waves in space into a signal, andoutputs the signal to the wireless communication unit 220.

(2) Wireless Communication Unit 220

The wireless communication unit 220 transmits and receives signals. Forexample, the wireless communication unit 220 receives a downlink signalfrom the base station 100 and transmits an uplink signal to the basestation 100.

(3) Storage Unit 230

The storage unit 230 stores a program and data for operation of theterminal apparatus 200.

(4) Processing Unit 240

The processing unit 240 provides various functions of the terminalapparatus 200. The processing unit 240 includes an information acquiringunit 241 and the reception processing unit 243. Note that the processingunit 240 may further include other components in addition to suchcomponents. That is, the processing unit 240 may also perform operationsother than operations of such components.

Specific operations of the information acquiring unit 241 and thereception processing unit 243 will be described below in detail.

<<4. Technical Features>>

Next, technical features according to an embodiment of the presentdisclosure will be described with reference to FIGS. 10 to 24.

(1) Allocation of Antenna Port to Directional Beam

In the embodiment of the present disclosure, the antenna port isallocated (assigned) to each of the plurality of predefined directionalbeams (for transmission).

For transmission by the directional beams included in the plurality ofdirectional beams, the antenna port allocated to the directional beam isused.

(a) Allocation of Same Antenna Port

For example, the plurality of directional beams include two or moredirectional beams allocated to the same antenna port. In other words,the same antenna port is allocated to two or more directional beamsamong the plurality of directional beams.

For example, the two or more directional beams are directional beamsthat do not interfere with each other. Specifically, for example, thetwo or more directional beams are directional beams whose radiationdirections are more or less different (for example, directional beamswhose radiation direction differs by a predetermined degree or more).

Accordingly, for example, it is possible to reduce the number of antennaports. As a result, the resources necessary for transmitting thereference signal can be suppressed. In other words, the overheadassociated with the reference signal can be suppressed.

Here, the “directional beams that do not interfere with each other” maybe “directional beams assumed not to interfere with each other” or“directional beams that actually do not interfere with each other” (asdetermined by measurement or the like).

(b) Allocation of Different Antenna Ports

For example, the plurality of directional beams include a set of two ormore directional beams to which different antenna ports are allocated.In other words, different antenna ports are allocated to two or moredirectional beams among the plurality of directional beams.

For example, the set of two or more directional beams is a set ofdirectional beams that interfere with each other. Specifically, forexample, the set of two or more directional beams is a set ofdirectional beams in which the radiation directions are similar (forexample, directional beams whose radiation direction does not differ bya predetermined degree or more).

Accordingly, for example, it is possible to suppress/remove interferencebetween directional beams.

Here, the “directional beams that interfere with each other” may be“directional beams assumed to interfere with each other” or “directionalbeams that actually interfere with each other” (as determined bymeasurement or the like).

(c) Specific Example

Specific examples of directional beam and antenna ports will bedescribed with reference to FIGS. 10 and 11. FIG. 10 is an explanatorydiagram for describing an example of directional beams formed by a basestation 100, and FIG. 11 is an explanatory diagram for describing anexample of antenna ports allocated to directional beams.

Referring to FIG. 10, in this example, the base station 100 formsdirectional beams 301, 303, 305, and 307. The radiation direction of thedirectional beam 301 and the radiation direction of the directional beam303 are close to each other, but the radiation direction of thedirectional beam 305 and the radiation direction of the directional beam307 are greatly different. In other words, interference may occurbetween the directional beam 301 and the directional beam 303, but apossibility of interference occurring between the directional beam 301(or the directional beam 303) and either of the directional beam 305 andthe directional beam 307 is considerably low. Further, the radiationdirection of the directional beam 305 and the radiation direction of thedirectional beam 307 are greatly different from each other. In otherwords, a possibility of interference occurring between the directionalbeam 305 and the directional beam 307 is very low.

If these points are taken into consideration, for example, an antennaport A is allocated to a beam 0 (the directional beam 301), a beam 2(the directional beam 305), and a beam 3 (the directional beam 307) asillustrated in FIG. 11. In other words, the same antenna port isallocated to the directional beams that do not interfere with eachother. On the other hand, an antenna port B is allocated to the beam 1(the directional beam 303). In other words, different antenna ports areallocated to a set of directional beams that interfere with each other(the directional beam 301 and the directional beam 303).

(d) Transmission by Each Beam in Resources for Transmitting ReferenceSignal

An example of transmission by each beam in resources for transmitting areference signal will be described with reference to FIG. 12. FIG. 12 isan explanatory diagram for describing an example of transmission by eachbeam in resources for transmitting the reference signal. Referring toFIG. 12, DMRS resources 51 for the antenna port A (that is, resourcesfor transmitting the DMRS using the antenna port A) and DMRS resources53 for the antenna port B (that is, resources for transmitting the DMRSusing the antenna port B) are illustrated. The DMRS resources 51 and theDMRS resources 53 are orthogonal to each other (in at least one of thetime/frequency resources and the code sequence).

In this example, the base station 100 transmits the DMRS by the beam 0(the directional beam 301), the beam 2 (the directional beam 305), andthe beam 3 (the directional beam 397) in the DMRS resources 51 using theantenna port A. On the other hand, the base station 100 transmits theDMRS by the beam 1 (the directional beam 303) in the DMRS resources 53using the antenna port B.

In addition, interference may occur between the beam 0 (the directionalbeam 301) and the beam 1 (the directional beam 303). For this reason, inorder to prevent interference with the DMRS transmitted by the beam 1(the directional beam 303), the base station 100 does not transmit anysignal by the beam 0 (the directional beam 301) in the DMRS resources53. In other words, the DMRS resources 53 become blank for the beam 0.Further, in order to prevent interference with the DMRS transmitted bythe beam 0 (the directional beam 301), the base station 100 does nottransmit any signal by the beam 1 (the directional beam 303) in the DMRSresources 51. In other words, the DMRS resources 51 become blank for thebeam 1.

Note that a possibility of interference occurring between the beam 1(the directional beam 303) and either of the beam 2 (the directionalbeam 305) and the beam 3 (the directional beam 307) is considerably low.Therefore, the base station 100 can transmit the data signal by each ofthe beam 2 (the directional beam 305) and the beam 3 (the directionalbeam 307) in the DMRS resources 53 using the antenna port A.Accordingly, for example, the overhead differs according to each beam,and the overhead associated with the transmission of the referencesignal can be further suppressed.

(e) Allocating Entity

For example, the base station 100 (the allocating unit 151) allocates anantenna port to each of the plurality of directional beams.

Alternatively, an operator of the base station 100 may allocate anantenna port to each of the plurality of directional beams.

(2) Notification of Antenna-Related Information

In the embodiment of the present disclosure, the base station 100 (theinformation acquiring unit 153) acquires the antenna-related informationrelated to the antenna port allocated to the directional beam fortransmission by the directional beam. The base station 100 (thenotifying unit 155) notifies the terminal apparatus 200 of theantenna-related information.

On the other hand, the terminal apparatus 200 (the information acquiringunit 241) acquires the antenna-related information. Then, the terminalapparatus 200 (the reception processing unit 243) performs the receptionprocess on the basis of the antenna-related information.

Accordingly, for example, it is possible to actually allocate theantenna port to each directional beam as described above. Therefore, thenumber of antenna ports can be decreased. As a result, the resourcesnecessary for transmitting the reference signal can be suppressed. Inother words, the overhead associated with the reference signal can besuppressed. Further, the interference between directional beams can besuppressed/removed.

(a) Directional Beam

For example, the directional beam is included in the plurality ofdirectional beams which are predefined.

(b) Antenna Port

For example, the antenna port is a virtual antenna corresponding to oneor more physical antennas or antenna elements. As an example, theantenna port corresponds to two or more antenna elements included in anarray antenna.

(c) Antenna-Related Information (First Example)

As a first example, the directional beam is a directional beam fortransmitting a signal to the terminal apparatus 200. In other words, thebase station 100 (the notifying unit 155) notifies the terminalapparatus 200 of the antenna-related information related to the antennaport allocated to the directional beam for transmitting the signal tothe terminal apparatus 200.

Referring again to FIGS. 10 and 11, as an example, the directional beamfor transmitting a signal to the terminal apparatus 200 is the beam 0(the directional beam 301), and the antenna-related information isinformation related to the antenna port A allocated to the beam 0.

(c-1) Specific Information

For example, the antenna-related information related to the antenna portincludes information indicating the antenna port.

Specifically, for example, the information is a port number of theantenna port. Referring again to FIG. 11, as an example, theantenna-related information is the port number of the antenna port Aallocated to the beam 0 (the directional beam 301).

Accordingly, for example, the terminal apparatus 200 can recognize theantenna port used for transmission of a signal destined for the ownterminal apparatus. Therefore, the terminal apparatus 200 can specifyresources in which the reference signal (for example, the DMRS) istransmitted using the antenna port and demodulate and decode a signaltransmitted by the directional beam on the basis of a reception resultof the reference signal.

(c-2) Resources for Transmission of Reference Signal

For example, resources for transmitting the reference signal using theantenna port are predefined. Accordingly, for example, the terminalapparatus 200 is able to recognize the resources when the antenna portis known.

Alternatively, instead of predefining the resources, the antenna-relatedinformation may include information indicating the resources fortransmitting the reference signal using the antenna port. Accordingly,for example, it is possible to flexibly decide the resources fortransmitting the reference signal. In this case, the antenna-relatedinformation may include the information indicating the antenna port asdescribed above or may not include the information indicating theantenna port.

For example, the resources are a combination of time/frequency resourcesand a code sequence.

(c-3) Notification Technique

For example, the base station 100 (the notifying unit 155) notifies theterminal apparatus 200 of the antenna-related information throughsignaling (for example, radio resource control (RRC) signaling) destinedfor the terminal apparatus 200. In other words, the base station 100(the notifying unit 155) notifies the terminal apparatus 200 of theantenna-related information through a signaling message (for example, anRRC message) destined for the terminal apparatus 200.

Alternatively, the base station 100 (the notifying unit 155) may notifythe terminal apparatus 200 of the antenna-related information throughdownlink control information (DCI) destined for the terminal apparatus200. The DCI is information transmitted on a physical downlink controlchannel (PDCCH).

(c-4) Further Notification of Other Antenna-Related Information

For example, the base station 100 (the information acquiring unit 153)acquires other antenna-related information related to the antenna portallocated to another directional beam for transmission by the otherdirectional beam. Then, the base station 100 (the notifying unit 155)further notifies the terminal apparatus 200 of the other antenna-relatedinformation.

For example, the other directional beam is a directional beam thatinterferes with the directional beam. Referring again to FIGS. 10 and11, as an example, the directional beam is the beam 0 (the directionalbeam 301), and the other directional beam is the beam 1 (the directionalbeam 303). The other antenna-related information is information relatedto the antenna port B allocated to the beam 1.

For example, the other antenna-related information also includesinformation similar to the antenna-related information. Specifically,for example, the other antenna-related information includes theinformation indicating the antenna port allocated to the otherdirectional beam (for example, the port number of the antenna port B orthe like).

For example, the base station 100 (the notifying unit 155) notifies theterminal apparatus 200 of the other antenna-related information throughsignaling destined for the terminal apparatus 200. Alternatively, thebase station 100 (the notifying unit 155) notifies the terminalapparatus 200 of the other antenna-related information through the DCIdestined for the terminal apparatus 200.

Accordingly, for example, the terminal apparatus 200 can remove a signaltransmitted by another directional beam as interference.

(C-5) Operation of Terminal Apparatus

The Reception Process Based on the Antenna-Related Information

As described above, the terminal apparatus 200 (the reception processingunit 243) performs the reception process on the basis of theantenna-related information.

For example, the terminal apparatus 200 specifies an antenna portallocated to a directional beam for transmitting a signal destined forthe terminal apparatus 200 from the antenna-related information, andspecifies resources for transmitting the reference signal (for example,the DMRS) using the antenna port. Then, the terminal apparatus 200restores the phase and the amplitude of the data signal destined for theterminal apparatus 200 on the basis of the reception result of thereference signal transmitted in the resources, and demodulates anddecodes the data signal.

Reception Process Based on Other Antenna-Related Information

For example, the terminal apparatus 200 (the reception processing unit243) performs the reception process further on the basis of otherantenna-related information.

For example, the terminal apparatus 200 specifies an antenna portallocated to another directional beam that interferes with thedirectional beam from the other antenna-related information, andspecifies resources for transmitting the reference signal (for example,the DMRS) using the antenna port. Then, the terminal apparatus 200generates the signal transmitted by the other directional beam as aninterference signal on the basis of the reception result of thereference signal transmitted in the resources and removes theinterference signal from a reception signal. Then, the terminalapparatus 200 demodulates and decodes the data signal destined for theterminal apparatus 200 from the signal after the removal.

(d) Antenna-Related Information (Second Example)

As a second example, the base station 100 (the information acquiringunit 153) may acquire the antenna-related information for each of theplurality of directional beams which are predefined. Then, the basestation 100 (the notifying unit 155) may notify the terminal apparatus200 of the antenna-related information for each of the plurality ofdirectional beams.

Referring again to FIGS. 10 and 11, as an example, the plurality ofdirectional beams may include the beam 0 (the directional beam 301), thebeam 1 (the directional beam 303), the beam 2 (the directional beam305), and the beam 3 (the directional beam 307). The base station 100(the notifying unit 155) may notify the terminal apparatus 200 of theantenna-related information for each of the beam 0, the beam 1, the beam2, the beam 3, and the like. Further, the “antenna-related informationfor the beam 0” means “antenna-related information related to theantenna port allocated to the beam 0.”

(d-1) Specific Information

The antenna-related information related to the directional beam mayinclude the information indicating the antenna port allocated to thedirectional beam (for example, the port number of the antenna port).Further, the antenna-related information related to the directional beammay further include the information indicating the directional beam (forexample, a precoding matrix indicator (PMI) corresponding to thedirectional beam or the like). Specifically, the antenna-relatedinformation may include a set of the information indicating thedirectional beam and the information indicating the antenna port.

Referring again to FIG. 11, as an example, the antenna-relatedinformation for the beam 0 may include a set of the PMI corresponding tothe beam 0 and the port number of the antenna port A allocated to thebeam 0.

(d-2) Resources for Transmission of Reference Signal

The resources for transmitting the reference signal using the antennaport may be predefined.

Alternatively, resources for transmitting the reference signal using theantenna port may not be predefined. In this case, the antenna-relatedinformation related to the antenna port may include the informationindicating the resources for transmitting the reference signal using theantenna port. In this case, the antenna-related information may includethe information indicating the antenna port as described above or maynot include information indicating the antenna port.

Note that the resources may be a combination of time/frequency resourcesand a code sequence.

(d-3) Notification Technique

The base station 100 (the notifying unit 155) may notify the terminalapparatus 200 of the antenna-related information related to each of theplurality of directional beams through signaling (for example, the RRCsignaling) destined for the terminal apparatus 200. In other words, thebase station 100 (the notifying unit 155) notifies the terminalapparatus 200 of the antenna-related information related to each of theplurality of directional beams through a signaling message (for example,the RRC message) destined for the terminal apparatus 200.

Alternatively, the base station 100 (the notifying unit 155) may notifythe terminal apparatus 200 of the antenna-related information throughsystem information (for example, a system information block (SIB)).

(d-4) Specifying of Directional Beam

The base station 100 (the notifying unit 155) may notify the terminalapparatus 200 of beam information indicating a directional beam fortransmitting a signal destined for the terminal apparatus 200.

Alternatively, the terminal apparatus 200 may select an appropriatedirectional beam for transmitting a signal destined for the terminalapparatus 200 on the basis of a result of measurement (for example,measurement based on the reference signal (for example, the CSI-RS)) andreport information (report information) indicating the appropriatedirectional beam to the base station 100. Then, the base station 100 maytransmit a signal to the terminal apparatus 200 by the appropriatedirectional beam. For the selection of the directional beam, the basestation 100 may transmit the reference signal by a directional beam, andthe terminal apparatus 200 may evaluate the directional beam on thebasis of a reception result of the reference signal. Alternatively, theterminal apparatus 200 may virtually evaluate the directional beam onthe basis of a reception result of a non-directional reference signaland a set of weight coefficients corresponding to the directional beam.

Accordingly, for example, the terminal apparatus 200 can specify thedirectional beam for transmitting the signal destined for the terminalapparatus 200.

Note that the base station 100 (the notifying unit 155) may also notifythe terminal apparatus 200 of other beam information indicating anotherdirectional beam. The other directional beam may be a directional beamthat interferes with the directional beam for transmitting the signaldestined for the terminal apparatus 200.

(d-5) Operation of Terminal Apparatus

As described above, the terminal apparatus 200 (the reception processingunit 243) may perform the reception process on the basis of theantenna-related information.

The terminal apparatus 200 may specify the antenna port allocated to thedirectional beam for transmitting the signal destined for the terminalapparatus 200 on the basis of the beam information and theantenna-related information. Further, the terminal apparatus 200 mayspecify the resources for transmitting the reference signal (forexample, the DMRS) using the antenna port. The terminal apparatus 200may restore the phase and the amplitude of the data signal destined forthe terminal apparatus 200 on the basis of the reception result of thereference signal transmitted in the resources, and demodulate and decodethe data signal

Further, the terminal apparatus 200 may specify the antenna portallocated to another directional beam that interferes with thedirectional beam from other beam information and the antenna-relatedinformation. Further, the terminal apparatus 200 may specify theresources for transmitting the reference signal (for example, the DMRS)using the antenna port. Then, the terminal apparatus 200 may generatethe signal transmitted by the other directional beam as an interferencesignal on the basis of the reception result of the reference signaltransmitted in the resources and remove the interference signal from thereception signal. Then, the terminal apparatus 200 may demodulate anddecode the data signal destined for the terminal apparatus 200 from thesignal after the removal.

(3) Dynamic/Quasi-Static Antenna Port Allocation

For example, the base station 100 (the allocating unit 151) dynamicallyor quasi-statically allocates an antenna port to each of the pluralityof directional beams which are predefined. In other words, the basestation 100 (the allocating unit 151) does not statically (that is,fixedly) allocate an antenna port to each of the plurality ofdirectional beams but changes an antenna port allocated to each of theplurality of directional beams.

For example, the base station 100 (the allocating unit 151) allocates anantenna port to each of the plurality of directional beams on the basisof interference information reported from the terminal apparatus 200.For example, the terminal apparatus 200 measures interference on thebasis of the CSI-RS and reports a result of the measurement to the basestation 100 as the interference information. As an example, the terminalapparatus 200 measures reception power of each directional beam on thebasis of the CSI-RS and reports information indicating one or moredirectional beams (for example, one or more interference beams) withhigh reception power to the base station 100 as the interferenceinformation.

For example, the base station 100 allocates an antenna port to each ofthe plurality of directional beams so that different antenna ports areallocated to two directional beams that interfere with each other.

More specifically, for example, the base station 100 changes thedirectional beam in accordance with a change in the position of theterminal apparatus 200 located in the cell 101. Further, for example,the base station 100 changes the number of directional beams inaccordance with a change in the number of terminal apparatuses 200located in the cell 101. Therefore, for example, the base station 100changes the directional beam or the number of directional beams, and asa result, more than a certain amount of interference may occur betweenthe two directional beams to which the same antenna port is allocated.In this case, the base station 100 allocates different antenna ports tothe two directional beams. In this case, the number of antenna ports maybe increased.

For example, even when the base station 100 changes the directional beamor the number of directional beams, and another antenna port isaccordingly allocated to one or more directional beams to which acertain antenna port is allocated, interference does not occur. Then,the base station 100 allocates another antenna port to the one or moredirectional beams. In this case, the certain antenna port becomesunnecessary, and the number of antenna ports can be decreasedaccordingly.

Accordingly, for example, the antenna port is allocated in view of anactual interference situation. As a result, interference betweendirectional beams can be suppressed. Further, the number of antennaports can be suppressed and the overhead associated with the referencesignal can be suppressed.

(4) Various Examples of Antenna Port Allocation

In the embodiment of the present disclosure, there may be variousantenna port allocations. Next, first to fourth techniques of allocatingthe antenna port will be exemplarily described.

(a) First Technique

For example, the plurality of predefined directional beams include afirst directional beam, a second directional beam, and a thirddirectional beam. The first directional beam is adjacent to the seconddirectional beam and the third directional beam. The second directionalbeam and the third directional beam are not adjacent to each other.Here, “the first directional beam is adjacent to the second directionalbeam” means that the radiation direction of the first directional beamis adjacent to the radiation direction of the second directional beam ina set of discrete radiation directions.

Particularly, in a first technique, a first antenna port is allocated tothe first directional beam, and a second antenna port different from thefirst antenna port is allocated to the second directional beam and thethird directional beam. A specific example will be described below withreference to FIGS. 13 to 17.

(a-1) Example of Directional Beam

FIG. 13 is an explanatory diagram for describing an example ofdirectional beams formed by the base station 100. Referring to FIG. 13,in this example, the base station 100 forms directional beams 311, 313,and 315. The directional beam 313 is adjacent to the directional beam311 and the directional beam 315, and the directional beam 311 and thedirectional beam 315 are not adjacent to each other. For example, thedirectional beam 313 is the first directional beam, the directional beam313 is the second directional beam, and the directional beam 315 is thethird directional beam.

(a-2) Other Technique (Technique of Preparing Different Antenna Portsfor Each Directional Beam)

FIG. 14 is an explanatory diagram for describing an example of anantenna port allocated to each directional beam according to anothertechnique (a technique of preparing a different antenna port for eachdirectional beam). Referring to FIG. 14, in this technique, the antennaport A is allocated to the beam 0 (the directional beam 311), theantenna port B is allocated to the beam 1 (the directional beam 313),and the antenna port C is allocated to the beam 2 (the directional beam315).

FIG. 15 is an explanatory diagram for describing an example oftransmission by respective beams in another technique. Referring to FIG.15, DMRS resources 51 for the antenna port A, DMRS resources 53 for theantenna port B, and DMRS resources 55 for the antenna port C areillustrated. The DMRS resources 51, the DMRS resources 53, and the DMRSresources 55 are orthogonal to one another. In this example, the basestation 100 transmits the DMRS by the beam 0 (the directional beam 311)in the DMRS resources 51 using the antenna port A. Further, the basestation 100 transmits the DMRS by the beam 1 (the directional beam 313)in the DMRS resources 53 using the antenna port B. Further, the basestation 100 transmits the DMRS by the beam 2 (the directional beam 315)in the DMRS resources 55 using the antenna port C. As a result, it isnecessary to prepare many DMRS resources for transmission of the DMRS,and the overhead is increased.

(a-3) First Technique of Allocating Antenna Port

FIG. 16 is an explanatory diagram for describing an example of antennaports allocated to respective directional beams by the first technique.Referring to FIG. 16, in this technique, the antenna port A is allocatedto the beam 0 (the directional beam 311) and the beam 2 (the directionalbeam 315), and the antenna port B is allocated to the beam 1 (thedirectional beam 313).

FIG. 17 is an explanatory diagram for describing an example oftransmission by respective beams in the first technique. Referring toFIG. 15, DMRS resources 51 for the antenna port A and DMRS resources 53for the antenna port B are illustrated. The DMRS resources 51 and theDMRS resources 53 are orthogonal to each other. In this example, thebase station 100 transmits the DMRS by the beam 0 (the directional beam311) and the beam 2 (the directional beam 313) in the DMRS resources 51using the antenna port A. Further, the base station 100 transmits theDMRS by the beam 1 (the directional beam 313) in the DMRS resources 53using the antenna port B. As a result, a smaller number of DMRSresources are prepared for transmission of the reference signal, and theoverhead is decreased. In this example, for example, the antenna port Bis the first antenna port, and the antenna port A is the second antennaport.

As described above, according to the first technique, the antenna portis shared by the directional beams, and thus the number of antenna portscan be reduced.

(a-4) Further Specific Features

As further specific features, one of the two directional beams adjacentto each other among the plurality of directional beams may be adirectional beam to which the first antenna port is allocated, and theother of the two arbitrary directional beams may be a directional beamto which the second antenna port is allocated. As described above, onlythe first antenna port and the second antenna port may be prepared, andthe antenna ports may be alternately allocated. Accordingly, forexample, the number of antenna ports is two.

(b) Second Technique

In a second technique, further features are added in addition to thefirst technique.

For example, the first directional beam is adjacent to the seconddirectional beam and the third directional beam in one of the horizontaldirection and the vertical direction. Further, the plurality ofdirectional beams include a fourth directional beam and a fifthdirectional beam to which the first directional beam is adjacent in theother of the horizontal direction and the vertical direction. The fourthdirectional beam and the fifth directional beam are not adjacent to eachother.

Particularly, in the second technique, the fourth directional beam andthe fifth directional beam are directional beams to which the secondantenna port is allocated.

Further, for example, one of two arbitrary directional beams which areadjacent to each other among the plurality of directional beams may be adirectional beam to which the first antenna port is allocated, and theother of the two arbitrary directional beams may be a directional beamto which the second antenna port is allocated. A specific example willbe described below with reference to FIG. 18.

FIG. 18 is an explanatory diagram for describing an example of antennaports allocated to respective directional beams in accordance with thesecond technique. Referring to FIG. 18, 64 (8×8) directional beamshaving directivity in the horizontal direction and the verticaldirection are illustrated. For example, directional beams 321, 323, 325,and 327 are directional beams arranged in the horizontal direction, anddirectional beams 329, 323, 331, and 333 are directional beams arrangedin the vertical direction. The antenna port A is allocated to thedirectional beams 321, 325, 329, and 331, and the antenna port B isallocated to the directional beams 323, 327, and 333. In this example,for example, the directional beam 323 is a first directional beam, andthe directional beams 321, 325, 329, and 331 are the second directionalbeam, the third directional beam, the fourth directional beam, and thefifth directional beam. Further, the antenna port B is the first antennaport, and the antenna port A is the second antenna port.

As described above, according to the second technique, the antenna portis shared by the directional beams, and the number of antenna ports canbe reduced. For example, the number of antenna ports can be two.

Practically, three or more antenna ports can be prepared in view ofreflection of directional beam or the like. Further, in an environmentwith less reflection of directional beams, only two antenna ports may beprepared.

(c) Third Technique

For example, the plurality of directional beams include a first numberof consecutive directional beams. Particularly, in a third technique,the first number of different antenna ports are allocated to the firstnumber of consecutive directional beams. For example, the first numberof consecutive directional beams are consecutive in one of thehorizontal direction and the vertical direction. Here, “consecutivedirectional beams” means directional beams having consecutive radiationdirections in a set of discrete radiation directions.

For example, the same antenna port is allocated to the directional beamwhich is away by the first number among the consecutive directionalbeams.

(c-1) Specific Example

A specific example of the directional beam and the antenna port will bedescribed with reference to FIGS. 19 and 20. FIG. 19 is an explanatorydiagram for describing an example of directional beams formed by thebase station 100, and FIG. 20 is an explanatory diagram for describingan example of antenna ports allocated to the respective directionalbeams in accordance with the third technique. Referring to FIG. 19, inthis example, the base station 100 forms six consecutive directionalbeams 331, 333, 335, 337, 339, and 341 in the horizontal direction.Further, referring to FIG. 20, in this example, the antenna port A isallocated to a beam 0 (the directional beam 331) and a beam 3 (thedirectional beam 337). Further, the antenna port B is allocated to abeam 1 (the directional beam 333) and a beam 4 (the directional beam339). Further, the antenna port C is allocated to a beam 2 (thedirectional beam 335) and a beam 5 (the directional beam 341). Asdescribed above, the same antenna port is allocated to the directionalbeam that is 3 away among the consecutive directional beams. Further,three different antenna ports are allocated to three consecutivedirectional beams. For example, three different antenna ports areallocated to the beam 0 (the directional beam 331), the beam 1 (thedirectional beam 333), and the beam 2 (the directional beam 335).Further, three different antenna ports are allocated to the beam 1 (thedirectional beam 333), the beam 2 (the directional beam 335), and thebeam 3 (the directional beam 337). Further, three different antennaports are allocated to the beam 2 (the directional beam 335), the beam 3(the directional beam 337), and the beam 4 (the directional beam 339).Further, three different antenna ports are allocated to the beam 3 (thedirectional beam 337), the beam 4 (the directional beam 339), and thebeam 5 (the directional beam 341).

As described above, according to the third technique, different antennaports are allocated to a predetermined number (first number) ofdirectional beams whose radiation directions are close to each other,and thus interference is suppressed. Further, since the same antennaport is allocated to the directional beam which is away by thepredetermined number, the number of antenna ports can be reduced. As aresult, the overhead can be suppressed.

(c-2) Transmission by Respective Beams in Resources for TransmittingReference Signal

An example of transmission by respective beams in resources fortransmitting the reference signal will be described with reference toFIG. 21. FIG. 21 is an explanatory diagram for describing an example oftransmission by respective beams in the third technique. Referring toFIG. 21, DMRS resources 51 for the antenna port A, DMRS resources 53 forthe antenna port B, and DMRS resources 55 for the antenna port C areillustrated. The DMRS resources 51, the DMRS resources 53, and the DMRSresources 55 are orthogonal to one another (in at least one of thetime/frequency resources and the code sequence).

In this example, the base station 100 transmits the DMRS by the beam 0(the directional beam 331) and the beam 3 (the directional beam 337) inthe DMRS resources 51 using the antenna port A. Further, the basestation 100 transmits the DMRS by the beam 1 (the directional beam 333)and the beam 4 (the directional beam 339) in the DMRS resources 53 usingthe antenna port B. Further, the base station 100 transmits the DMRS bythe beam 2 (the directional beam 335) and the beam 5 (the directionalbeam 341) in the DMRS resources 55 using the antenna port C.

The DMRS resources 51 are blank for the beams 1, 2, 3, and 5, the DMRSresources 53 are blank for the beams 0, 2, 3, and 5, and the DMRSresources 55 are blank for the beams 0, 1, 3, and 4. Accordingly,interference on the DMRS is prevented.

(d) Fourth Technique

In a fourth technique, additional features are added in addition to thethird technique.

For example, the plurality of directional beams include a second numberof consecutive directional beams different from the first number ofconsecutive directional beams. Particularly, in the second technique,the second number of different antenna ports are allocated to the secondnumber of consecutive directional beams. For example, the second numberof consecutive directional beams are consecutive in one of thehorizontal direction and the vertical direction.

(d-1) Specific Example

A specific example of the directional beam and the antenna port will bedescribed with reference to FIGS. 22 and 23. FIG. 22 is an explanatorydiagram for describing an example of directional beams formed by thebase station 100, and FIG. 23 is an explanatory diagram for describingan example of the antenna ports allocated to the respective directionalbeams in accordance with the fourth technique. Referring to FIG. 22, inthis example, the base station 100 forms seven consecutive directionalbeams 351, 353, 355, 357, 359, 361, and 363 in the horizontal direction.Further, referring to FIG. 23, in this example, the antenna port A isallocated to a beam 0 (the directional beam 351) and a beam 3 (thedirectional beam 357). Further, the antenna port B is allocated to thebeam 1 (the directional beam 353) and a beam 4 (the directional beam359). Further, the antenna port C is allocated to a beam 2 (thedirectional beam 355) and a beam 5 (the directional beam 361). Further,the antenna port D is allocated to a beam 6 (the directional beam 363).In this example, three different antenna ports are allocated to threearbitrary consecutive directional beams among the beams 0 to 5. On theother hand, since the beam 6 is likely to interfere with the beam 3 (orexample, due to interference) as well as the beams 4 and 5, fourdifferent antenna ports are allocated to the beams 3 to 6.

As described above, according to the fourth technique, when apossibility of the occurrence of interference is different depending ona direction from the base station 100, it is possible to change thenumber of antenna ports to be allocated in accordance with thepossibility of the occurrence of interference. For example, a smallnumber of antenna ports may be allocated for a direction in which thepossibility of the occurrence of interference is low, and more antennaports may be allocated for a direction in which the possibility of theoccurrence of interference is high. Accordingly, for example, theinterference can be appropriately suppressed.

(d-2) Transmission by Respective Beams in Resources for TransmittingReference Signal

An example of transmission by respective beams in resources fortransmitting a reference signal will be described with reference to FIG.24. FIG. 24 is an explanatory diagram for describing an example oftransmission by respective beams in the fourth technique. Referring toFIG. 24, DMRS resources 51 for the antenna port A, DMRS resources 53 forthe antenna port B, DMRS resources 55 for the antenna port C, and DMRSresources 57 for the antenna port D are illustrated. The DMRS resources51, the DMRS resources 53, the DMRS resources 55, and the DMRS resources57 are orthogonal to one another (in at least one of the time/frequencyresources and the code sequence).

In this example, the base station 100 transmits the DMRS by the beam 0(the directional beam 351) and the beam 3 (the directional beam 357) inthe DMRS resources 51 using the antenna port A. Further, the basestation 100 transmits the DMRS by the beam 1 (the directional beam 353)and the beam 4 (the directional beam 359) in the DMRS resources 53 usingthe antenna port B. Further, the base station 100 transmits the DMRS bythe beam 2 (the directional beam 355) and the beam 5 (the directionalbeam 361) in the DMRS resources 55 using the antenna port C. Further,the base station 100 transmits the DMRS by the beam 6 (the directionalbeam 363) in the DMRS resources 57 using the antenna port D.

The DMRS resources 51 are blank for the beams 1, 2, 3, 5, and 6, theDMRS resources 53 are blank for beams 0, 2, 3, 5, and 6, the DMRSresources 55 are blank for the beams 0, 1, 3, 4, and 6, and the DMRSresources 57 are blank for the beams 3, 4, and 5. Accordingly, theinterference on the DMRS is prevented.

Note that the possibility of interference occurring between the beams 0,1, and 2 (the directional beams 351, 353, and 355) and the beam 6 (thedirectional beam 363) is low. Therefore, the base station 100 cantransmit the data signal by the beam 0 (the directional beam 351) in theDMRS resources 57 using the antenna port A. Further, the base station100 can transmit the data signal by the beam 1 (the directional beam353) in the DMRS resources 57 using the antenna port B. Further, thebase station 100 can transmit the data signal by the beam 2 (thedirectional beam 353) in the DMRS resources 57 using the antenna port C.Accordingly, for example, the overhead differs according to each beam,and the overhead related to transmission of the reference signal isfurther suppressed.

<<5. Processing Flow>>

Next, a processing flow according to the embodiment of the presentdisclosure will be described with reference to FIGS. 25 to 27.

(1) Transmission/Reception Process

(a) First Example

FIG. 25 is a flowchart illustrating a first example of a schematic flowof a transmission/reception process according to the embodiment of thepresent disclosure.

The base station 100 notifies the terminal apparatus 200 of a CSI-RSconfiguration (S401). Further, the base station 100 transmits the CSI-RS(S403).

The terminal apparatus 200 performs measurement on the basis of theCSI-RS (S405). Then, the terminal apparatus 200 selects an appropriatedirectional beam on the basis of a result of the measurement (S407).Then, the terminal apparatus 200 reports information indicating theappropriate beam to the base station 100 as the report information(S409).

The base station 100 decides the appropriate directional beam as thedirectional beam for transmitting the signal destined for the terminalapparatus 200 and acquires the antenna-related information for theappropriate directional beam (S411). The antenna-related information isinformation related to the antenna port allocated to the appropriatedirectional beam for transmission by the appropriate directional beam.For example, the antenna-related information includes information (forexample, the port number) indicating the antenna port allocated to theappropriate directional beam.

The base station 100 notifies the terminal apparatus 200 of theantenna-related information (S413). For example, the base station 100notifies the terminal apparatus 200 of the antenna-related informationthrough signaling (for example, the RRC signaling) destined for theterminal apparatus 200. Alternatively, the base station 100 may notifythe terminal apparatus 200 of the antenna-related information throughthe DCI destined for the terminal apparatus 200.

Further, the base station 100 transmits the DMRS and the data signaldestined for the terminal apparatus 200 by the appropriate directionalbeam (S415).

The terminal apparatus 200 performs the reception process on the basisof the antenna-related information (S417).

Note that the base station 100 may notify the terminal apparatus 200 ofanother antenna-related information related to the antenna portallocated to another directional beam. The other directional beam may bea directional beam that interferes with the appropriate directionalbeam. Then, the terminal apparatus 200 may perform the reception processfurther on the basis of the other antenna-related information.

(b) Second Example

FIG. 26 is a flowchart illustrating a second example of a schematic flowof the transmission/reception process according to the embodiment of thepresent disclosure.

Here, description of steps S435 to S443 illustrated in FIG. 26 is thesame as description of steps S401 to S409 illustrated in FIG. 25.Therefore, description will proceed focusing on steps S431, S433, andS445 to S449.

The base station 100 acquires the antenna-related information for eachof the plurality of predefined directional beams (S431). For example,the antenna-related information for the directional beams included inthe plurality of directional beams is information related to the antennaport allocated to the directional beam for transmission by thedirectional antenna. For example, the antenna-related informationincludes a combination of the information indicating the directionalbeam (for example, PMI) and the information indicating the antenna portallocated to the directional beam (for example, the port number).

The base station 100 notifies the terminal apparatus 200 of theantenna-related information for the plurality of directional beams(S433). For example, the base station 100 notifies the terminalapparatus 200 of the antenna-related information for the plurality ofdirectional beams through signaling (for example, the RRC signaling)destined for the terminal apparatus 200. Alternatively, the base station100 may notify the terminal apparatus 200 of the antenna-relatedinformation through the system information (for example, an SIB).

The base station 100 decides the appropriate directional beam (S441)selected by the terminal apparatus 200 as a directional beam fortransmitting the signal destined for the terminal apparatus 200 andnotifies the terminal apparatus 200 of the beam information indicatingthe appropriate directional beam (S445).

Further, the base station 100 transmits the DMRS and the data signaldestined for the terminal apparatus 200 by the appropriate directionalbeam (S447).

The terminal apparatus 200 performs the reception process on the basisof the beam information and the antenna-related information (S449).

Note that the base station 100 may notify the terminal apparatus 200 ofother beam information indicating another directional beam together. Theother directional beam may be a directional beam that interferes withthe appropriate directional beam. Then, the terminal apparatus 200 mayperform the reception process further on the basis of the other beaminformation.

Further, the base station 100 may not notify the terminal apparatus 200of the beam information. Instead, the terminal apparatus 200 may regardthe appropriate directional beam selected by the terminal apparatus 200as the directional beam for transmitting a signal destined for theterminal apparatus 200.

(2) Antenna Port Allocation Process

FIG. 27 is a flowchart illustrating an example of a schematic flow of anantenna port allocation process according to the embodiment of thepresent disclosure.

The base station 100 notifies the terminal apparatus 200 of the CSI-RSconfiguration (S461). Further, the base station 100 transmits the CSI-RS(S463).

The terminal apparatus 200 performs interference measurement on thebasis of the CSI-RS (S465). For example, the terminal apparatus 200measures reception power of each directional beam on the basis of theCSI-RS. Then, the terminal apparatus 200 reports information indicatingone or more directional beams (for example, one or more interferencebeams) with high reception power to the base station 100 as the reportinformation (S467).

The base station 100 reallocates the antenna port to the directionalbeam on the basis of the report information from one or more terminalapparatuses 200 (S469).

<<6. Application Examples>>

The technique according to the present disclosure is applicable tovarious products. The base station 100 may also be implemented, forexample, as any type of evolved Node B (eNB) such as macro eNBs andsmall eNBs. Small eNBs may cover smaller cells than the macrocells ofpico eNBs, micro eNBs, or home (femt) eNBs. Instead, the base station100 may be implemented as another type of base station such as Nodes Bor base transceiver stations (BTSs). The base station 100 may includethe main apparatus (which is also referred to as base station apparatus)that controls wireless communication and one or more remote radio heads(RRHs) that are disposed at different locations from that of the mainapparatus. Also, various types of terminals described below may functionas the base station 100 by temporarily or semi-permanently executing thefunctionality of the base station. Furthermore, at least some ofcomponents of the base station 100 may be realized in a base stationapparatus or a module for a base station apparatus.

Further, the terminal apparatus 200 may be implemented as a mobileterminal such as smartphones, tablet personal computers (PCs), notebookPCs, portable game terminals, portable/dongle mobile routers, anddigital cameras, or an in-vehicle terminal such as car navigationapparatuses. The terminal apparatus 200 may be implemented as a machinetype communication (MTC) for establishing a machine to machinecommunication (M2M). Furthermore, at least some of components of theterminal apparatus 200 may be implemented as a module (e.g. integratedcircuit module constituted with a single die) that is mounted on theseterminals.

<6.1. Application Examples for Base Station>

(1) First Application Example

FIG. 28 is a block diagram illustrating a first example of a schematicconfiguration of an eNB to which the technology according to the presentdisclosure may be applied. An eNB 800 includes one or more antennas 810and a base station apparatus 820. Each antenna 810 and the base stationapparatus 820 may be connected to each other via an RF cable.

Each of the antennas 810 includes a single or a plurality of antennaelements (e.g. a plurality of antenna elements constituting a MIMOantenna) and is used for the base station apparatus 820 to transmit andreceive a wireless signal. The eNB 800 may include the plurality of theantennas 810 as illustrated in FIG. 28, and the plurality of antennas810 may, for example, correspond to a plurality of frequency bands usedby the eNB 800. It should be noted that while FIG. 28 illustrates anexample in which the eNB 800 includes the plurality of antennas 810, theeNB 800 may include the single antenna 810.

The base station apparatus 820 includes a controller 821, a memory 822,a network interface 823, and a wireless communication interface 825.

The controller 821 may be, for example, a CPU or a DSP, and operatesvarious functions of an upper layer of the base station apparatus 820.For example, the controller 821 generates a data packet from data in asignal processed by the wireless communication interface 825, andtransfers the generated packet via the network interface 823. Thecontroller 821 may generate a bundled packet by bundling data from aplurality of base band processors to transfer the generated bundledpacket. The controller 821 may also have a logical function ofperforming control such as radio resource control, radio bearer control,mobility management, admission control, and scheduling. The control maybe performed in cooperation with a surrounding eNB or a core network.The memory 822 includes a RAM and a ROM, and stores a program executedby the controller 821 and a variety of control data (such as, forexample, terminal list, transmission power data, and scheduling data).

The network interface 823 is a communication interface for connectingthe base station apparatus 820 to the core network 824. The controller821 may communicate with a core network node or another eNB via thenetwork interface 823. In this case, the eNB 800 may be connected to acore network node or another eNB through a logical interface (e.g. S1interface or X2 interface). The network interface 823 may be a wiredcommunication interface or a wireless communication interface forwireless backhaul. When the network interface 823 is a wirelesscommunication interface, the network interface 823 may use a higherfrequency band for wireless communication than a frequency band used bythe wireless communication interface 825.

The wireless communication interface 825 supports a cellularcommunication system such as long term evolution (LTE) or LTE-Advanced,and provides wireless connection to a terminal located within the cellof the eNB 800 via the antenna 810. The wireless communication interface825 may typically include a base band (BB) processor 826 and an RFcircuit 827. The BB processor 826 may, for example, performencoding/decoding, modulation/demodulation, multiplexing/demultiplexing,and the like, and performs a variety of signal processing on each layer(e.g. L1, medium access control (MAC), radio link control (RLC), andpacket data convergence protocol (PDCP)). The BB processor 826 may havepart or all of the logical functions as described above instead of thecontroller 821. The BB processor 826 may be a module including a memoryhaving a communication control program stored therein, a processor toexecute the program, and a related circuit, and the function of the BBprocessor 826 may be changeable by updating the program. The module maybe a card or blade to be inserted into a slot of the base stationapparatus 820, or a chip mounted on the card or the blade. Meanwhile,the RF circuit 827 may include a mixer, a filter, an amplifier, and thelike, and transmits and receives a wireless signal via the antenna 810.

The wireless communication interface 825 may include a plurality of theBB processors 826 as illustrated in FIG. 28, and the plurality of BBprocessors 826 may, for example, correspond to a plurality of frequencybands used by the eNB 800. The wireless communication interface 825 mayalso include a plurality of the RF circuits 827, as illustrated in FIG.28, and the plurality of RF circuits 827 may, for example, correspond toa plurality of antenna elements. FIG. 28 illustrates an example in whichthe wireless communication interface 825 includes the plurality of BBprocessors 826 and the plurality of RF circuits 827, but the wirelesscommunication interface 825 may include the single BB processor 826 orthe single RF circuit 827.

In the eNB 800 illustrated in FIG. 28, one or more components (theallocating unit 151, the information acquiring unit 153 and/or thenotifying unit 155) included in the processing unit 150 described withreference to FIG. 8 may be implemented in the wireless communicationinterface 825. Alternatively, at least some of the components may beimplemented in the controller 821. As an example, the eNB 800 may beequipped with a module including a part (for example, a BB processor826) or all of the wireless communication interface 825 and/or thecontroller 821, and the one or more components may be implemented in themodule. In this case, the module stores a program causing a processor tofunction as the one or more components (that is, a program causing theprocessor to execute operations of the one or more components) andexecute the program. As another example, a program causing a processorto function as the one or more components described above may beinstalled in the eNB 800, and the wireless communication interface 825(for example, the BB processor 826) and/or the controller 821 mayexecute the program. As described above, the eNB 800, the base stationapparatus 820, or the above module may be provided as an apparatusequipped with the one or more components, and a program causing aprocessor to function as the one or more components may be provided.Further, a readable recording medium including the above programrecorded therein may be provided.

In addition, in the eNB 800 shown in FIG. 28, the wireless communicationunit 120 described with reference to FIG. 8 may be implemented by thewireless communication interface 825 (for example, the RF circuit 827).Moreover, the antenna unit 110 may be implemented by the antenna 810. Inaddition, the network communication unit 130 may be implemented by thecontroller 821 and/or the network interface 823.

(2) Second Application Example

FIG. 29 is a block diagram illustrating a second example of a schematicconfiguration of an eNB to which the technology according to the presentdisclosure may be applied. An eNB 830 includes one or more antennas 840,a base station apparatus 850, and an RRH 860. Each of the antennas 840and the RRH 860 may be connected to each other via an RF cable. The basestation apparatus 850 and the RRH 860 may be connected to each other bya high speed line such as optical fiber cables.

Each of the antennas 840 includes a single or a plurality of antennaelements (e.g. antenna elements constituting a MIMO antenna), and isused for the RRH 860 to transmit and receive a wireless signal. The eNB830 may include a plurality of the antennas 840 as illustrated in FIG.29, and the plurality of antennas 840 may, for example, correspond to aplurality of frequency bands used by the eNB 830. FIG. 29 illustrates anexample in which the eNB 830 includes the plurality of antennas 840, butthe eNB 830 may include the single antenna 840.

The base station apparatus 850 includes a controller 851, a memory 852,a network interface 853, a wireless communication interface 855, and aconnection interface 857. The controller 851, the memory 852, and thenetwork interface 853 are the same as the controller 821, the memory822, and the network interface 823 described with reference to FIG. 28.

The wireless communication interface 855 supports a cellularcommunication system such as LTE and LTE-Advanced, and provides wirelessconnection to a terminal located in a sector corresponding to the RRH860 via the RRH 860 and the antenna 840. The wireless communicationinterface 855 may typically include a BB processor 856. The BB processor856 is the same as the BB processor 826 described with reference to FIG.28 except that the BB processor 856 is connected to an RF circuit 864 ofthe RRH 860 via the connection interface 857. The wireless communicationinterface 855 may include a plurality of the BB processors 856, asillustrated in FIG. 29, and the plurality of BB processors 856 may, forexample, correspond to a plurality of frequency bands used by the eNB830 respectively. FIG. 29 illustrates an example in which the wirelesscommunication interface 855 includes the plurality of BB processors 856,but the wireless communication interface 855 may include the single BBprocessor 856.

The connection interface 857 is an interface for connecting the basestation apparatus 850 (wireless communication interface 855) to the RRH860. The connection interface 857 may be a communication module forcommunication on the high speed line which connects the base stationapparatus 850 (wireless communication interface 855) to the RRH 860.

Further, the RRH 860 includes a connection interface 861 and a wirelesscommunication interface 863.

The connection interface 861 is an interface for connecting the RRH 860(wireless communication interface 863) to the base station apparatus850. The connection interface 861 may be a communication module forcommunication on the high speed line.

The wireless communication interface 863 transmits and receives awireless signal via the antenna 840. The wireless communicationinterface 863 may typically include the RF circuit 864. The RF circuit864 may include a mixer, a filter, an amplifier and the like, andtransmits and receives a wireless signal via the antenna 840. Thewireless communication interface 863 may include a plurality of the RFcircuits 864 as illustrated in FIG. 29, and the plurality of RF circuits864 may, for example, correspond to a plurality of antenna elements.FIG. 29 illustrates an example in which the wireless communicationinterface 863 includes the plurality of RF circuits 864, but thewireless communication interface 863 may include the single RF circuit864.

In the eNB 830 illustrated in FIG. 29, one or more components (theallocating unit 151, the information acquiring unit 153 and/or thenotifying unit 155) included in the processing unit 150 described withreference to FIG. 8 may be implemented in the wireless communicationinterface 855 and/or the wireless communication interface 863.Alternatively, at least some of the components may be implemented in thecontroller 851. As an example, the eNB 830 may be equipped with a moduleincluding a part (for example, a BB processor 856) or all of thewireless communication interface 855 and/or the controller 851, and theone or more components may be implemented in the module. In this case,the module stores a program causing a processor to function as the oneor more components (that is, a program causing the processor to executeoperations of the one or more components) and execute the program. Asanother example, a program causing a processor to function as the one ormore components described above may be installed in the eNB 830, and thewireless communication interface 855 (for example, the BB processor 856)and/or the controller 851 may execute the program. As described above,the eNB 830, the base station apparatus 850, or the above module may beprovided as an apparatus equipped with the one or more components, and aprogram causing a processor to function as the one or more componentsmay be provided. Further, a readable recording medium including theabove program recorded therein may be provided.

In addition, in the eNB 830 shown in FIG. 29, the wireless communicationunit 120 described with reference to FIG. 8 may be implemented by thewireless communication interface 863 (for example, the RF circuit 864).Moreover, the antenna unit 110 may be implemented by the antenna 840. Inaddition, the network communication unit 130 may be implemented by thecontroller 851 and/or the network interface 853.

<6.2. Application Examples for Terminal Apparatus>

(1) First Application Example

FIG. 30 is a block diagram illustrating an example of a schematicconfiguration of a smartphone 900 to which the technology according tothe present disclosure may be applied. The smartphone 900 includes aprocessor 901, a memory 902, a storage 903, an external connectioninterface 904, a camera 906, a sensor 907, a microphone 908, an inputdevice 909, a display device 910, a speaker 911, a wirelesscommunication interface 912, one or more antenna switches 915, one ormore antennas 916, a bus 917, a battery 918, and a secondary controller919.

The processor 901 may be, for example, a CPU or a system on chip (SoC),and controls the functions of an application layer and other layers ofthe smartphone 900. The memory 902 includes a RAM and a ROM, and storesa program executed by the processor 901 and data. The storage 903 mayinclude a storage medium such as semiconductor memories and hard disks.The external connection interface 904 is an interface for connecting thesmartphone 900 to an externally attached device such as memory cards anduniversal serial bus (USB) devices.

The camera 906 includes an image sensor such as charge coupled devices(CCDs) and complementary metal oxide semiconductor (CMOS), and generatesa captured image. The sensor 907 may include a sensor group including,for example, a positioning sensor, a gyro sensor, a geomagnetic sensor,and an acceleration sensor. The microphone 908 converts a sound that isinput into the smartphone 900 to an audio signal. The input device 909includes, for example, a touch sensor which detects that a screen of thedisplay device 910 is touched, a key pad, a keyboard, a button, or aswitch, and accepts an operation or an information input from a user.The display device 910 includes a screen such as liquid crystal displays(LCDs) and organic light emitting diode (OLED) displays, and displays anoutput image of the smartphone 900. The speaker 911 converts the audiosignal that is output from the smartphone 900 to a sound.

The wireless communication interface 912 supports a cellularcommunication system such as LTE or LTE-Advanced, and performs wirelesscommunication. The wireless communication interface 912 may typicallyinclude the BB processor 913, the RF circuit 914, and the like. The BBprocessor 913 may, for example, perform encoding/decoding,modulation/demodulation, multiplexing/demultiplexing, and the like, andperforms a variety of types of signal processing for wirelesscommunication. On the other hand, the RF circuit 914 may include amixer, a filter, an amplifier, and the like, and transmits and receivesa wireless signal via the antenna 916. The wireless communicationinterface 912 may be a one-chip module in which the BB processor 913 andthe RF circuit 914 are integrated. The wireless communication interface912 may include a plurality of BB processors 913 and a plurality of RFcircuits 914 as illustrated in FIG. 30. FIG. 30 illustrates an examplein which the wireless communication interface 912 includes a pluralityof BB processors 913 and a plurality of RF circuits 914, but thewireless communication interface 912 may include a single BB processor913 or a single RF circuit 914.

Further, the wireless communication interface 912 may support othertypes of wireless communication system such as a short range wirelesscommunication system, a near field communication system, and a wirelesslocal area network (LAN) system in addition to the cellularcommunication system, and in this case, the wireless communicationinterface 912 may include the BB processor 913 and the RF circuit 914for each wireless communication system.

Each antenna switch 915 switches a connection destination of the antenna916 among a plurality of circuits (for example, circuits for differentwireless communication systems) included in the wireless communicationinterface 912.

Each of the antennas 916 includes one or more antenna elements (forexample, a plurality of antenna elements constituting a MIMO antenna)and is used for transmission and reception of the wireless signal by thewireless communication interface 912. The smartphone 900 may include aplurality of antennas 916 as illustrated in FIG. 30. FIG. 30 illustratesan example in which the smartphone 900 includes a plurality of antennas916, but the smartphone 900 may include a single antenna 916.

Further, the smartphone 900 may include the antenna 916 for eachwireless communication system. In this case, the antenna switch 915 maybe omitted from a configuration of the smartphone 900.

The bus 917 connects the processor 901, the memory 902, the storage 903,the external connection interface 904, the camera 906, the sensor 907,the microphone 908, the input device 909, the display device 910, thespeaker 911, the wireless communication interface 912, and the secondarycontroller 919 to each other. The battery 918 supplies electric power toeach block of the smartphone 900 illustrated in FIG. 30 via a feederline that is partially illustrated in the figure as a dashed line. Thesecondary controller 919, for example, operates a minimally necessaryfunction of the smartphone 900 in a sleep mode.

In the smartphone 900 illustrated in FIG. 30, the information acquiringunit 241 and/or the reception processing unit 243 described above withreference to FIG. 9 may be mounted in the wireless communicationinterface 912. Alternatively, at least some of the components may bemounted in the processor 901 or the secondary controller 919. As anexample, the smartphone 900 may be equipped with a module including someor all components of the wireless communication interface 912 (forexample, the BB processor 913), the processor 901, and/or the secondarycontroller 919, and the information acquiring unit 241 and/or thereception processing unit 243 may be mounted in the module. In thiscase, the module may store a program causing the processor to functionas the information acquiring unit 241 and/or the reception processingunit 243 (that is, a program causing the processor to perform theoperation of the information acquiring unit 241 and/or the receptionprocessing unit 243) and execute the program. As another example, theprogram causing the processor to function as the information acquiringunit 241 and/or the reception processing unit 243 may be installed inthe smartphone 900, and the wireless communication interface 912 (forexample, the BB processor 913), the processor 901, and/or the secondarycontroller 919 may execute the program. As described above, thesmartphone 900 or the module may be provided as an apparatus includingthe information acquiring unit 241 and/or the reception processing unit243, and the program causing the processor to function as theinformation acquiring unit 241 and/or the reception processing unit 243may be provided. A readable recording medium in which the program isrecorded may be provided.

In addition, in the smartphone 900 shown in FIG. 30, the wirelesscommunication unit 220 described with reference to FIG. 9 may beimplemented by the wireless communication interface 912 (for example,the RF circuit 914). Moreover, the antenna unit 210 may be implementedby the antenna 916.

(2) Second Application Example

FIG. 31 is a block diagram illustrating an example of a schematicconfiguration of a car navigation apparatus 920 to which the technologyaccording to the present disclosure may be applied. The car navigationapparatus 920 includes a processor 921, a memory 922, a globalpositioning system (GPS) module 924, a sensor 925, a data interface 926,a content player 927, a storage medium interface 928, an input device929, a display device 930, a speaker 931, a wireless communicationinterface 933, one or more antenna switches 936, one or more antennas937, and a battery 938.

The processor 921 may be, for example, a CPU or an SoC, and controls thenavigation function and the other functions of the car navigationapparatus 920. The memory 922 includes a RAM and a ROM, and stores aprogram executed by the processor 921 and data.

The GPS module 924 uses a GPS signal received from a GPS satellite tomeasure the position (e.g. latitude, longitude, and altitude) of the carnavigation apparatus 920. The sensor 925 may include a sensor groupincluding, for example, a gyro sensor, a geomagnetic sensor, and abarometric sensor. The data interface 926 is, for example, connected toan in-vehicle network 941 via a terminal that is not illustrated, andacquires data such as vehicle speed data generated on the vehicle side.

The content player 927 reproduces content stored in a storage medium(e.g. CD or DVD) inserted into the storage medium interface 928. Theinput device 929 includes, for example, a touch sensor which detectsthat a screen of the display device 930 is touched, a button, or aswitch, and accepts operation or information input from a user. Thedisplay device 930 includes a screen such as LCDs and OLED displays, anddisplays an image of the navigation function or the reproduced content.The speaker 931 outputs a sound of the navigation function or thereproduced content.

The wireless communication interface 933 supports a cellularcommunication system such as LTE or LTE-Advanced, and performs wirelesscommunication. The wireless communication interface 933 may typicallyinclude the BB processor 934, the RF circuit 935, and the like. The BBprocessor 934 may, for example, perform encoding/decoding,modulation/demodulation, multiplexing/demultiplexing, and the like, andperforms a variety of types of signal processing for wirelesscommunication. On the other hand, the RF circuit 935 may include amixer, a filter, an amplifier, and the like, and transmits and receivesa wireless signal via the antenna 937. The wireless communicationinterface 933 may be a one-chip module in which the BB processor 934 andthe RF circuit 935 are integrated. The wireless communication interface933 may include a plurality of BB processors 934 and a plurality of RFcircuits 935 as illustrated in FIG. 31. FIG. 31 illustrates an examplein which the wireless communication interface 933 includes a pluralityof BB processors 934 and a plurality of RF circuits 935, but thewireless communication interface 933 may be a single BB processor 934 ora single RF circuit 935.

Further, the wireless communication interface 933 may support othertypes of wireless communication system such as a short range wirelesscommunication system, a near field communication system, and a wirelessLAN system in addition to the cellular communication system, and in thiscase, the wireless communication interface 933 may include the BBprocessor 934 and the RF circuit 935 for each wireless communicationsystem.

Each antenna switch 936 switches a connection destination of the antenna937 among a plurality of circuits (for example, circuits for differentwireless communication systems) included in the wireless communicationinterface 933.

Each of the antennas 937 includes one or more antenna elements (forexample, a plurality of antenna elements constituting a MIMO antenna)and is used for transmission and reception of the wireless signal by thewireless communication interface 933. The car navigation apparatus 920includes a plurality of antennas 937 as illustrated in FIG. 31. FIG. 31illustrates an example in which the car navigation apparatus 920includes a plurality of antennas 937, but the car navigation apparatus920 may include a single antenna 937.

Further, the car navigation apparatus 920 may include the antenna 937for each wireless communication system. In this case, the antenna switch936 may be omitted from a configuration of the car navigation apparatus920.

The battery 938 supplies electric power to each block of the carnavigation apparatus 920 illustrated in FIG. 31 via a feeder line thatis partially illustrated in the figure as a dashed line. The battery 938accumulates the electric power supplied from the vehicle.

In the car navigation apparatus 920 illustrated in FIG. 31, theinformation acquiring unit 241 and/or the reception processing unit 243described above with reference to FIG. 9 may be mounted in the wirelesscommunication interface 933. Alternatively, at least some of thecomponents may be mounted in the processor 921. As an example, the carnavigation apparatus 920 may be equipped with a module including some orall components of the wireless communication interface 933 (for example,the BB processor 934), and the information acquiring unit 241 and/or thereception processing unit 243 may be mounted in the module. In thiscase, the module may store a program causing the processor to functionas the information acquiring unit 241 and/or the reception processingunit 243 (that is, a program causing the processor to perform theoperation of the information acquiring unit 241 and/or the receptionprocessing unit 243) and execute the program. As another example, theprogram causing the processor to function as the information acquiringunit 241 and/or the reception processing unit 243 may be installed inthe car navigation apparatus 920, and the wireless communicationinterface 933 (for example, the BB processor 934) and/or the processor921 may execute the program. As described above, the car navigationapparatus 920 or the module may be provided as an apparatus includingthe information acquiring unit 241 and/or the reception processing unit243, and the program causing the processor to function as theinformation acquiring unit 241 and/or the reception processing unit 243may be provided. A readable recording medium in which the program isrecorded may be provided.

In addition, in the car navigation apparatus 920 shown in FIG. 31, thewireless communication unit 220 described with reference to FIG. 9 maybe implemented by the wireless communication interface 933 (for example,the RF circuit 935). Moreover, the antenna unit 210 may be implementedby the antenna 937.

The technology of the present disclosure may also be realized as anin-vehicle system (or a vehicle) 940 including one or more blocks of thecar navigation apparatus 920, the in-vehicle network 941, and a vehiclemodule 942. In other words, the in-vehicle system (or a vehicle) 940 maybe provided as a device which includes the information acquiring unit241 and/or the reception processing unit 243. The vehicle module 942generates vehicle data such as vehicle speed, engine speed, and troubleinformation, and outputs the generated data to the in-vehicle network941.

<<7. Conclusion>>

So far, each of devices and processes according to embodiments of thepresent disclosure have been described with reference to FIGS. 7 to 31.

According to the present disclosure, the base station 100 includes theinformation acquiring unit 153 that acquires the antenna-relatedinformation related to the antenna port allocated to the directionalbeam for transmission by the directional beam and the notifying unit 155that notifies the terminal apparatus 200 of the antenna-relatedinformation.

According to the embodiment of the present disclosure, the terminalapparatus 200 includes the information acquiring unit 241 that acquiresthe antenna-related information related to the antenna port allocated tothe directional beam for transmission by the directional beam and thereception processing unit 243 that performs the reception process.

Accordingly, it is possible to suppress the overhead related to thetransmission of the reference signal, for example, when beamforming isperformed.

The preferred embodiment(s) of the present disclosure has/have beendescribed above with reference to the accompanying drawings, whilst thepresent disclosure is not limited to the above examples. A personskilled in the art may find various alterations and modifications withinthe scope of the appended claims, and it should be understood that theywill naturally come under the technical scope of the present disclosure.

Although an example is described in which the system is a system that iscompliant with LTE, LTE-Advanced, or a communication scheme thatconforms to them, the present disclosure is not limited to such anexample. For example, the system may be a system that conforms toanother communication standard.

Further, it is not always necessary to execute the processing steps inthe processing in the present specification in chronological order inorder described in the flowcharts or the sequence diagrams. For example,the processing steps in the above-described processing may be executedin order different from the order described in the flowcharts or thesequence diagrams or may be executed in parallel.

In addition, a computer program for causing a processor (for example, aCPU, a DSP, or the like) provided in a device of the presentspecification (for example, a base station, a base station apparatus ora module for a base station apparatus, or a terminal apparatus or amodule for a terminal apparatus) to function as a constituent element ofthe device (for example, the allocating unit, the information acquiringunit, the notifying unit, the reception processing unit, or the like)(in other words, a computer program for causing the processor to executeoperations of the constituent element of the device) can also becreated. In addition, a recording medium in which the computer programis recorded may also be provided. Further, a device that includes amemory in which the computer program is stored and one or moreprocessors that can execute the computer program (a base station, a basestation apparatus or a module for a base station apparatus, or aterminal apparatus or a module for a terminal apparatus) may also beprovided. In addition, a method including an operation of theconstituent element of the device (for example, the allocating unit, theinformation acquiring unit, the notifying unit, the reception processingunit, or the like) is also included in the technology of the presentdisclosure.

Further, the effects described in this specification are merelyillustrative or exemplified effects, and are not limitative. That is,with or in the place of the above effects, the technology according tothe present disclosure may achieve other effects that are clear to thoseskilled in the art from the description of this specification.

Additionally, the present technology may also be configured as below.

(1) An apparatus, including:

-   -   an acquiring unit configured to acquire antenna-related        information related to an antenna port allocated to a        directional beam for transmission by the directional beam; and    -   a notifying unit configured to notify a terminal apparatus of        the antenna-related information.

(2) The apparatus according to (1),

-   -   in which the directional beam is a directional beam for        transmitting a signal to the terminal apparatus.

(3) The apparatus according to (2),

-   -   in which the acquiring unit acquires other antenna-related        information related to an antenna port allocated to another        directional beam for transmission by the other directional beam,        and    -   the notifying unit further notifies the terminal apparatus of        the other antenna-related information.

(4) The apparatus according to (1),

-   -   in which the acquiring unit acquires the antenna-related        information for each of a plurality of directional beams which        are predefined, and    -   the notifying unit notifies the terminal apparatus of the        antenna-related information for each of the plurality of        directional beams.

(5) The apparatus according to any one of (1) to (4),

-   -   in which the antenna-related information includes information        indicating the antenna port.

(6) The apparatus according to any one of (1) to (5),

-   -   in which resources for transmitting a reference signal using the        antenna port are predefined.

(7) The apparatus according to any one of (1) to (5),

-   -   in which the antenna-related information includes information        indicating resources for transmitting a reference signal using        the antenna port.

(8) The apparatus according to any one of (1) to (7),

-   -   in which the directional beam is included in a plurality of        directional beams which are predefined.

(9) The apparatus according to (8),

-   -   in which the plurality of directional beams include two or more        directional beams to which the same antenna port is allocated.

(10) The apparatus according to (9),

-   -   in which the two or more directional beams are directional beams        that do not interfere with each other.

(11) The apparatus according to any one of (8) to (10),

-   -   in which the plurality of directional beams include a set of two        or more directional beams to which different antenna ports are        allocated.

(12) The apparatus according to (11),

-   -   in which the set of two or more directional beams is a set of        directional beams that interfere with each other.

(13) The apparatus according to any one of (8) to (12),

-   -   in which the plurality of directional beams include a first        directional beam, a second directional beam, and a third        directional beam,    -   the first directional beam is adjacent to the second directional        beam and the third directional beam,    -   the second directional beam and the third directional beam are        not adjacent to each other,    -   the first directional beam is a directional beam to which a        first antenna port is allocated, and    -   the second directional beam and the third directional beam are        directional beams to which a second antenna port different from        the first antenna port is allocated.

(14) The apparatus according to (13),

-   -   in which the first directional beam is adjacent to the second        directional beam and the third directional beam in one of a        horizontal direction and a vertical direction,    -   the plurality of directional beams include a fourth directional        beam and a fifth directional beam which are adjacent to the        first directional beam in the other of the horizontal direction        and the vertical direction,    -   the fourth directional beam and the fifth directional beam are        not adjacent to each other, and    -   the fourth directional beam and the fifth directional beam are        directional beams to which the second antenna port is allocated.

(15) The apparatus according to any one of (8) to (12),

-   -   in which the plurality of directional beams include a first        number of consecutive directional beams, and    -   the first number of consecutive directional beams are        directional beams to which the first number of different antenna        ports are allocated.

(16) The apparatus according to (15),

-   -   in which the plurality of directional beams include a second        number of consecutive directional beams different from the first        number of consecutive directional beams, and    -   the second number of consecutive directional beams are        directional beams to which the second number of different        antenna ports are allocated.

(17) The apparatus according to any one of (8) to (16), furtherincluding

-   -   an allocating unit configured to dynamically or quasi-statically        allocate an antenna port to each of a plurality of directional        beams which are predefined.

(18) The apparatus according to (17),

-   -   in which the allocating unit allocates the antenna port to each        of the plurality of directional beams on the basis of        interference information reported from the terminal apparatus.

(19) The apparatus according to any one of (1) to (18),

-   -   in which the antenna port is a virtual antenna corresponding to        one or more physical antennas or antenna elements.

(20) An apparatus, including:

-   -   an acquiring unit configured to acquire antenna-related        information related to an antenna port allocated to a        directional beam for transmission by the directional beam; and    -   a reception processing unit configured to perform a reception        process on the basis of the antenna-related information.

(21) The apparatus according to (6) or (7),

-   -   in which the resources are a combination of time/frequency        resources and a code sequence.

(22) The apparatus according to (13) or (14),

-   -   in which one of two arbitrary directional beams which are        adjacent to each other among the plurality of directional beams        is a directional beam to which the first antenna port is        allocated, and    -   the other of the two arbitrary directional beams is a        directional beam to which the second antenna port is allocated.

(23) The apparatus according to (15) or (16),

-   -   in which the consecutive directional beams are consecutive in        one of a horizontal direction and a vertical direction.

(24) The apparatus according to any one of (1) to (19),

-   -   in which the apparatus is a base station, a base station        apparatus for the base station or a module for the base station        apparatus.

(25) The apparatus according to (20),

-   -   in which the apparatus is a terminal apparatus or a module for        the terminal apparatus.

(26) A method, including:

-   -   acquiring, by a processor, antenna-related information related        to an antenna port allocated to a directional beam for        transmission by the directional beam; and    -   notifying, by the processor, a terminal apparatus of the        antenna-related information.

(27) A program causing a processor to execute:

-   -   acquiring antenna-related information related to an antenna port        allocated to a directional beam for transmission by the        directional beam; and    -   notifying a terminal apparatus of the antenna-related        information.

(28) A readable recording medium having a program recorded thereon, theprogram causing a processor to execute:

-   -   acquiring antenna-related information related to an antenna port        allocated to a directional beam for transmission by the        directional beam; and    -   notifying a terminal apparatus of the antenna-related        information.

(29) A method, including:

-   -   acquiring, by a processor, antenna-related information related        to an antenna port allocated to a directional beam for        transmission by the directional beam; and    -   performing, by the processor, a reception process on the basis        of the antenna-related information.

(30) A program causing a processor to execute:

-   -   acquiring antenna-related information related to an antenna port        allocated to a directional beam for transmission by the        directional beam; and    -   performing a reception process on the basis of the        antenna-related information.

(31) A readable recording medium having a program recorded thereon, theprogram causing a processor to execute:

-   -   acquiring antenna-related information related to an antenna port        allocated to a directional beam for transmission by the        directional beam; and    -   performing a reception process on the basis of the        antenna-related information.

REFERENCE SIGNS LIST

-   -   1 system    -   100 base station    -   101 cell    -   151 allocating unit    -   153 information acquiring unit    -   155 notifying unit    -   200 base station    -   241 information acquiring unit    -   243 reception processing unit

1. An apparatus, comprising: a wireless communication interfaceconfigured to acquire antenna-related information related to an antennaport allocated to a channel, and notify a terminal apparatus of theantenna-related information, wherein the channel is included in aplurality of channels which are predefined and the plurality of channelsinclude two or more channels to which the same antenna port isallocated.
 2. The apparatus according to claim 1, wherein the channel isa channel for transmitting a signal to the terminal apparatus.
 3. Theapparatus according to claim 2, wherein the wireless communicationinterface is further configured to acquire other antenna-relatedinformation related to an antenna port allocated to another channel fortransmission by the other channel, and further notify the terminalapparatus of the other antenna-related information.
 4. The apparatusaccording to claim 1, wherein the wireless communication interface isfurther configured to acquire the antenna-related information for eachof a plurality of channels which are predefined, and notify the terminalapparatus of the antenna-related information for each of the pluralityof channels.
 5. The apparatus according to claim 1, wherein theantenna-related information includes information indicating the antennaport.
 6. The apparatus according to claim 1, wherein resources fortransmitting a reference signal using the antenna port are predefined.7. The apparatus according to claim 1, wherein the antenna-relatedinformation includes information indicating resources for transmitting areference signal using the antenna port.
 8. The apparatus according toclaim 1, wherein the two or more channels are channels that do notinterfere with each other.
 9. The apparatus according to claim 1,wherein the plurality of channels include a set of two or more channelsto which different antenna ports are allocated.
 10. The apparatusaccording to claim 9, wherein the set of two or more channels is a setof channels that interfere with each other.
 11. The apparatus accordingto claim 1, wherein the plurality of channels include a first channel, asecond channel, and a third channel, the first channel is adjacent tothe second channel and the third channel, the second channel and thethird channel are not adjacent to each other, the first channel is achannel to which a first antenna port is allocated, and the secondchannel and the third channel are channels to which a second antennaport different from the first antenna port is allocated.
 12. Theapparatus according to claim 11, wherein the first channel is adjacentto the second channel and the third channel in one of a horizontaldirection and a vertical direction, the plurality of channels include afourth channel and a fifth channel which are adjacent to the firstchannel in the other of the horizontal direction and the verticaldirection, the fourth channel and the fifth channel are not adjacent toeach other, and the fourth channel and the fifth channel are channels towhich the second antenna port is allocated.
 13. The apparatus accordingto claim 1, wherein the plurality of channels include a first number ofconsecutive channels, and the first number of consecutive channels arechannels to which the first number of different antenna ports areallocated.
 14. The apparatus according to claim 13, wherein theplurality of channels include a second number of consecutive channelsdifferent from the first number of consecutive channels, and the secondnumber of consecutive channels are channels to which the second numberof different antenna ports are allocated.
 15. The apparatus according toclaim 1, the wireless communication interface is further configured toconfigured to dynamically or quasi-statically allocate an antenna portto each of a plurality of channels which are predefined.
 16. Theapparatus according to claim 15, wherein the wireless communicationinterface is further configured to allocate the antenna port to each ofthe plurality of channels on the basis of interference informationreported from the terminal apparatus.
 17. The apparatus according toclaim 1, wherein the antenna port is a virtual antenna corresponding toone or more physical antennas or antenna elements.
 18. An apparatus,comprising: a wireless communication interface configured to acquireantenna-related information related to an antenna port allocated to achannel for transmission by the channel; and a reception processorconfigured to perform a reception process on the basis of theantenna-related information, wherein the channel is included in aplurality of channels which are predefined and the plurality of channelsinclude two or more channels to which the same antenna port isallocated.